The invention relates generally to automatic pulse cleaning systems for gas turbine inlet filter house elements.
To provide a safe and efficient operation, air entering a gas turbine for power generation applications is filtered. The gas turbine air inlet system may include an inlet filter house and associated ducting. The main ambient air inlet leads to a reduced outlet connected to a gas turbine inlet. Heating air is introduced via a manifold located in the inlet duct, downstream of one or more conventional silencers and the gas turbine inlet. Hot air is bled from the gas turbine compressor and carried via a conduit to the manifold, controlled by a pressure reducing valve. The hot air bled from the gas turbine compressor may also be mixed with ambient air.
Inlet filter houses are employed to filter out undesirable particulates from the inlet air before it reaches the turbine. See, for example, U.S. Pat. No. 6,875,256 and U.S. Published Application No. 2009/0107337 A1. In a typical installation, there may be between about 300 and about 800 filter elements attached to and projecting from a tube sheet, depending on the frame size of the turbine.
Systems are also provided for periodically and automatically cleaning these filter elements, typically in a programmed sequence that avoids downtime. Such systems are particularly critical in certain geographic areas that are both humid and dusty, where mud-like deposits can build up on the exterior of the filter elements. In some known pulse-cleaning systems, air supply pipes or manifolds extend across the tube sheet, with conical air pulse emitters or nozzles inserted in apertures in the pipes at each filter element outlet. The nozzle is centered on the filter element outlet and is designed to direct pulses of cleaning air into the filter element (counter to the normal flow of inlet air through the filter element) to thereby dislodge any solid particulates built up on the exterior of the element. Such arrangements are not particularly effective, however, when the filter elements are configured to have differing shapes in the axial direction. For example, one commonly used filter element has a cylindrical section at its inlet end, remote from the tube sheet, and a conical section at its outlet end where it is joined to the tube sheet. The air flow pattern of the pulse-cleaning air emitted from the single conical emitter or nozzle at the filter element outlet does not effectively clean both sections of this type of filter element.
There remains a need for a pulse-cleaning system that is especially suited for multi-section inlet filters of different shapes commonly used in gas turbine inlet filter houses.